Ampeg Svt-4 issues

[Tomas Garcia]

I'm having issues with my Ampeg SVT-4 Pro and I can't find anything online relating to whats happening!

Okay, so a few days ago during sound check for a show, I started checking my bass and it began cutting out. long story short I didn't end up using my head for the show.
SO! I come home, plug everything in again and start playing to see whats going on. with every note I play, I'm just getting fuzz coming through. the actual output volume is not very loud at all compared to when its functioning correctly. Every note I play, its just like a fuzzed/distorted note. I switched out the tubes with some brand new JJ 8803's and it didn't fix the problem. I plugged my head into other cabs just to see if it was a speaker problem and the same noise is coming out of other cabinets so its definitely the head. I was just wondering if anyone might know what the deal is. I have it plugged in mono, running into a 410x115 cab custom cab. Switched out cables, same output sound. switched out instruments, same output sounds. I've never had an issue with the head before.

Any input is appreciated!
Thanks.

ps. my bass is not active.

 

[B-string]

I've never heard of a 8803 made by JJ?

You might try using an instrument or pedal cable to loop the effects send and effects return, preamp out to power amp in after reinstalling the original tubes. You can play with your bass plugged into the effects return and/or power amp in to check the power amp. If it plays well that way (but not as loud) then the trouble is in the preamp, if it is still bad new tubes can't fix the SS output (power) amp.

 

[JimmyM]

Yep, try the effect loop thing. They can sometimes get corroded on the inside and require cleaning with Deoxit. Doing the cable between send and return opens them up if they're corroded. If it clears up, give them a little Deoxit or run the plugs in and out of each jack several times quickly. If not, you probably want to take it to a tech.